InterviewSolution
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For any sets A, B and C prove that:A × (B ∪ C) = (A × B) ∪ (A × C) |
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Answer» Given: A, B and C three sets are given. Need to prove: A × (B ∪ C) = (A × B) ∪ (A × C) Let us consider, (x, y)∈A × (B ∪ C) ⇒ x∈A and y∈(B ∪ C) ⇒ x∈A and (y∈B or y∈C) ⇒ (x∈A and y∈B) or (x∈A and y∈C) ⇒ (x, y)∈(A × B) or (x, y)∈(A × C) ⇒ (x, y)∈(A × B) ∪ (A × C) From this we can conclude that, ⇒ A × (B ∪ C) ⊆ (A × B) ∪ (A × C) ---- (1) Let us consider again, (a, b)∈(A × B) ∪ (A × C) ⇒ (a, b)∈(A × B) or (a, b)∈(A × C) ⇒ (a∈A and b∈B) or (a∈A and b∈C) ⇒ a∈A and (b∈B or b∈C) ⇒ a∈A and b∈(B ∪ C) ⇒ (a, b) ∈A × (B ∪ C) From this, we can conclude that, ⇒ (A × B) ∪ (A × C) ⊆ A × (B ∪ C) ---- (2) Now by the definition of the set we can say that, from (1) and (2), A × (B ∪ C) = (A × B) ∪ (A × C) [Proved] |
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